The purpose of this study was to evaluate contrast enhancement patterns on three-dimensional (3D) black blood (BB) contrast-enhanced magnetic resonance (MR) imaging in patients with occlusion or stenosis of the anterior intracranial artery.
From January 2018 to January 2020 we retrospectively reviewed stroke 3D BB contrast-enhanced MR imaging and MR angiography findings of patients visiting the emergency room for evaluation of non-traumatic brain lesions. In total, 92 patients with positive findings on 3D BB contrast-enhanced MR imaging were enrolled in this study. We divided the enrolled group according to whether MR angiography findings suggested complete occlusion, high-grade stenosis (51-99 %), or low-grade stenosis (10-50 %).
Of 92 patients, 33 had complete occlusion in the anterior intracranial artery, 36 had high-grade stenosis, and 23 had low-grade stenosis. The complete occlusion group showed concentric and segmental enhancement on 3D BB enhanced MR imaging. The high-grade stenosis group frequently showed concentric and focal enhancement. The high signal vessel sign in the complete occlusion group was significantly higher compared to the stenosis group (p < 0.001). The contrast ratio between the lesion and pituitary gland in the occlusion group was significantly lower than that of the stenosis group (p < 0.05).
Bright contrast enhancement and high signal vessel sign on 3D BB contrast enhanced MR imaging are related to contrast stagnation of the occlusion site and slow flow of a distal portion of the occlusion site.